- Author: Help Desk Team
If you have a history of “worms” in your apples, pears, or English walnuts, and have felt perplexed as to how to manage this problem, the very first step is to understand what is happening. When one understands that, the management becomes more understandable and approachable.
The “worms” are actually caterpillars, the immature stage of an adult moth. The life cycle is egg, larva (caterpillar), pupa, adult. The adult moth is mottled gray and small (½ to ¾ inch) and therefore hard to see and often goes unnoticed.
The adult female moth lays her eggs on or near developing fruit. The egg hatches and the caterpillar immediately will chew its way into the fruit where it lives and feeds. Entry holes are referred to as “stings” and typically exhibit a sawdust like residue called “frass”. If one sees a sting, the larva has already entered the fruit and is impervious to insecticidal sprays.
When it is ready to pupate, it will chew its way out and drop to the ground where it pupates in soil or leaf debris or under tree bark. After pupation an adult emerges and starts the cycle all over again.
The rate of development varies with temperature, proceeding more rapidly in warmer weather and climates. Depending upon the climate, codling moths can have two, three, and sometimes four generations per year. Our county has warmer climates inland and cooler climates by the coast. This means adult moths will start flying sooner and have more generations in the warmer areas and start flying later and have fewer generations in the cooler areas. Adult moths can start flying and laying eggs as early as March. The link below shows the approximate timing of the multiple generations.
https://ipm.ucanr.edu/PMG/PESTNOTES/pni7412-3.html
Codling moths can be difficult to manage, and a goal of 100% undamaged fruit may be unrealistic. A more reasonable goal would be to harvest enough undamaged fruit to meet your needs. In most backyard situations, the best course of action would be to combine a variety of the following non-chemical and low toxicity chemical methods early in the season.
Non-chemical:
- Pheromone traps (sticky traps laced with female pheromone to attract males) are not an effective management approach by themselves. They may be helpful if multiple traps are placed in a tree, but primarily they are used to monitor when adults are flying in order to time chemical applications. Traps can be purchased at most home and garden stores or online.
- Thinning your crop is important. The moths are most attracted to the place where two apples touch. Four to eight weeks after bloom, thin the fruit to only one per cluster, about every 6 inches.
- If you have thinned your fruit you may want to go one step further by “bagging” it. Although tedious and time consuming, placing bags over individual fruits early in the season, when the fruit is ½ to 1 inch in diameter, provides excellent control. The bag could be paper or cotton string. The link below provides a drawing of the bagging process. https://ipm.ucanr.edu/PMG/PESTNOTES/pni7412-2.html
- Beginning about six to eight weeks after bloom, and continuing every week or two throughout the season, check fruit on the tree for signs of damage (stings). Remove and destroy any infested fruit. Do not put the culled fruit in your backyard composting system, rather place it in green waste so it gets removed from your property.
- Since pupation takes place in litter on ground under the tree, keep the area continuously clean throughout the season, even though winter.
Low toxicity chemicals:
- CYD-X is a biological insecticide, a granulosis virus that affects only codling moth caterpillars. It kills by ingestion, therefore it must be ingested by the caterpillar prior to or as entering the fruit. To achieve this, it needs to be applied weekly beginning at the time of egg hatch. CYD-X is primarily available online.
- Spinosad is a biological insecticide, a bacterium that is toxic to insects in general. It kills by both contact and ingestion, therefore it needs to be applied at 10-day intervals beginning at the time of egg hatch. Spinosad is readily available at most home and garden stores.
- Adding 1% horticultural oil to either of the above improves effectiveness.
- Identifying the timing of egg hatch is key to the success of chemical applications. Egg hatch can be estimated by visually monitoring first stings or by using the UC Degree Day Calculator for codling moth https://ipm.ucanr.edu/calludt.cgi/DDMODEL?MODEL=CM&CROP=landscape
It is important to begin implementing control measures early in the season. The link below to the UC Integrated Pest Management website provides the detailed information you will need for implementation of your codling moth management program.
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7412.html
Photo credits: Three photos above: Copyright UC Regents - photographer Jack Kelly Clark
Help Desk of the UC Master Gardeners of Contra Costa County (EDC)
- Author: Help Desk Team
Aphids can be a scourge in the garden. There are over 4,000 species of aphids in the world, but fortunately only(!) about 250 species are attracted to the plants we grow in our gardens and landscapes.
Aphids are small, slow-moving insects that come in a variety of colors—green, yellow, brown, red, or black. They sometimes match the color of the plant they feed on, but not always. They have long legs and antennae, and usually have a pair of cornicles (tube-like structures) sticking out of their hind end. No other insects have cornicles. Some adult aphids have wings—this can occur when populations are high or during spring and fall—that can allow them to disperse to other plants.
Aphid reproduction is interesting. Adult females can give birth to up to 12 live offspring each day without mating. During warm weather, many aphid species can grow from newborn nymph to reproductive adult in a week. No wonder it seems like they appear overnight.
Aphids are attracted to plants on which they can feed. Plants that are actively growing are prime targets. Right now, these include plants in our winter gardens such as kale and broccoli and landscape plants such as roses, but also the many winter weeds growing abundantly in many neighborhoods.
Aphids have sucking mouth parts, somewhat like little straws. They use them to suck sap (which is a plant's sugar source). What they excrete is commonly referred to as ‘honeydew' which contains sugar and is therefore sticky. Ants are attracted to this honeydew and will actively “farm” the aphids and protect them against natural predators.
Many plants, especially trees and shrubs, can survive just fine with low to moderate numbers of leaf-feeding aphids. Damage can occur with larger populations. Yellowing leaves and stunted growth are common.
Aphids can also transmit viruses from plant to plant on many vegetable crops and ornamental plants. Symptoms can include mottled, yellow, or curled leaves, along with stunted growth.
Controlling aphids
Understanding their life cycle is key to their management. By checking plants twice a week while they are growing rapidly, you can catch infestations early. With small populations of wingless aphids, hosing them off with a strong stream of water works well. Once off the plants, aphids are unlikely to be able to return. You can also prune out the most infested parts. Make sure you also remove nearby weeds that can serve as a reservoir of new infestations.
Natural enemies are important for aphid control. Parasitic wasps lay eggs inside live aphids, causing them to turn into mummies. You can recognize these by light-colored aphid bodies with circular holes on top where the wasp has emerged. Lady beetles (especially the larvae), syrphid fly larvae, and green lacewings are voracious eaters of aphids. See this website: https://ipm.ucanr.edu/natural-enemies/
If spraying with water is not effective enough, insecticidal soaps and oils are the best choices for most situations. Oils include petroleum-based horticultural oils or plant-derived oils such as neem or canola oil. These products kill primarily by smothering the aphid, so thorough coverage of infested foliage is required. Soaps and oils kill only those aphids present on the day they are sprayed, so applications may need to be repeated. Although these products can kill some natural enemies that are present on the plant and hit by the spray, they don't leave a toxic residue.
It is easier to manage aphids earlier in an infestation than later when populations are high. Some aphids cause leaves to curl around them, protecting them from sprays and beneficial insects.
Prevention
- When you purchase new plants, inspect them carefully.
- Don't over-fertilize. Excess fertilizers, especially too much nitrogen, can stimulate plants to put out lush new growth that will entice aphids to set up home.
- Excessive pruning can also stimulate plants to put out attractive new growth.
- Use a row cover, especially on seedlings and new plants. This will keep out aphids but also protect from other pests.
- Control ants that can protect aphids.
For more information, check these websites:
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html#TABLE1
https://ipm.ucanr.edu/QT/aphidscard.html
Help Desk of the UC Master Gardeners of Contra Costa County (SEH)


- Author: Help Desk Team
We often get questions at the help desk from local gardeners who have lost many or sometimes even all their newly planted vegetable seedlings to one malady or another. Whether you have grown them from seed and tended your precious seedlings for many weeks, or have purchased them as young plants, this can be a heart-breaking occurrence. Here are seven steps you can take to give your young plants the best chance to survive and thrive.
Be patient and wait until the soil is the optimum temperature.
This applies for both purchased plants and for home-started seedlings. Your plants may have grown large enough to go into the ground, but if the outdoor temperatures are not yet at the optimal range, don't be tempted to plant them yet! When planted in soil that is too cold, many summer vegetable plants will just not grow. They are also more susceptible to being damaged or killed by fungal diseases. How does one know if the soil is the right temperature? The best way is to use a soil thermometer. A good kitchen thermometer will also work, although you may want to have one that is designated for use only in the garden. If you don't have a thermometer, watch for daytime high temperatures to remain consistently above 60 degrees and nighttime temperatures above 50 degrees. For more information on this, you may want to review our previous blog posting published on February 20th entitled: “Indoor Seed Starting."
Cool-season vegetables such as peas, cabbage, lettuce, carrots, cauliflower, broccoli, beets, and Swiss chard will do best when average temperatures range from 55 - 75ºF. Warm-season vegetables prefer temperatures that range from 65 - 95ºF. Examples of these are eggplants, tomatoes, beans, squash, melons, and peppers. Best planting times will differ for many vegetable varieties. Check seed packets or the planting guide listed below for information on the best dates for planting in your area.
CCC Vegetable Planting Guide-Interior Regions
CCC Vegetable Planting Guide-Coastal Regions
Avoid letting plants become pot bound.
Move your plants into containers that give them more room for healthy root growth. Transplanting into 4-inch, quart, and even gallon sizes is often necessary. Use a good quality soilless potting mix and avoid planting mixes and garden soil. To check if your plant needs a larger pot, gently tap the sides of the container it is in and carefully slide it out (soil, roots, and all) to look at the root growth. Transplant into larger containers before the roots begin to circle the edge of the soil, create a mat of roots at the bottom of the container, or grow out of the drain holes. Pot bound, stressed plants will often have early flower and fruit development. This can stunt their growth and impact the plant's health as well as reducing future harvests.
Harden off young plants to prepare them for their life outdoors.
Sunscald is a common problem in young plants and seedlings that have suddenly received more sunlight than they were previously accustomed to getting. Sunscald causes areas on the leaf to dry out and die, turning thin and papery and a white or light tan color. Most seedlings will bounce back from a moderate amount of sunscald damage and continue to grow new, healthy leaves. When the damage is so extensive that all or nearly all the leaf surfaces or areas of the stem are affected, the plant may not be able to survive.
To avoid this problem, plants must be hardened off. This is a process used to acclimate young plants and seedlings to the conditions outdoors. For seedlings that have been grown in a greenhouse, indoors under lights, or other protected environment, this is a crucial step. The hardening off process will take about 10 days to two weeks. Here is an excellent article from Penn State Extension with step-by-step instructions on how to harden off plants.
https://extension.psu.edu/hardening-transplants
Keep your plants safe from hungry pests- snails, slugs, earwigs, and birds.
Even the most experienced gardeners will lose some of their young vegetable plants to one or more hungry garden pests. My first suggestion is to always have a few extra plants to replace those that may get eaten. My second is if you have had problems in the past with one or more pests consuming your vegetable seedlings, start taking steps to control them before you plant. Don't wait until the damage is already done. The methods of controlling many of the pests are similar and include keeping your garden free of plant debris and favored hiding places, trapping, barriers, and baits. Baits that are safe for children, pets, and wildlife are available to the homeowner, and are very effective. Because they can take several days to take effect, it is best to use them in conjunction with the other suggested control methods. The best time to start using these control methods is several days to one week before planting.
Birds can also be a serious pest in the vegetable garden- especially early in the season as many vegetable starts are a favorite food. While there are many products advertised to scare birds away and keep them from eating your plants, bird netting is the solution that I find to be most effective. Make sure that the netting is raised above the plants to keep birds from reaching through to eat, and securely staked to the ground so that they cannot get underneath. Check your netting regularly, keep netting stretched snugly over supports, and avoid any loose ends that can trap and kill birds, lizards, and other wildlife. As plants mature, they are less attractive to the birds, and netting can often be removed. See one of our earlier blogs for more information on protecting your plants from a variety of pests: https://ucanr.edu/blogs/CCMGBlog/index.cfm?tagname=birds
Space requirements for healthy vegetable plants
Before planting it is important to consider the mature size of the plants, and the space necessary for them to grow and flourish. Vegetable plants do not do well in overcrowded situations where they need to compete for nutrients, water, and sunlight. They will tend to be stunted and much less productive than those that have plenty of room. For information on space requirements for a variety of vegetable plants, click here: https://ucanr.edu/sites/MarinMG/files/343708.pdf.
Transplanting tips, suggestions
If transplanting from flats with several plants growing in them, be sure to take up some soil with each plant as you carefully remove each one from the flat. If transplanting single plants from individual containers, try to remove them from the container with the soil as intact as possible to avoid root damage. This will be much easier to do if the plants have been watered recently and the soil in the container is well moistened. Choose a cool, cloudy day to transplant or wait until late in the day when the sun is low in the sky. Don't forget to thoroughly water your plants immediately after planting. If you have questions about the best way to handle and transplant seedlings, see this video from the Master Gardener Program of San Luis Obispo County:
https://www.youtube.com/watch?v=72dqbPZFgFY
Give your plants some shade after planting in the garden.
It is difficult to completely avoid damaging a plant's root hairs when transplanting. Root hairs are necessary to take up water and nutrients. Giving your plants some shade in the hottest part of the day for the first 5–7 days after transplanting will help keep them cooler while they regrow their root hairs. Garden shade structures do not have to be complicated and can either be purchased or made at home with items you may already have. Shade cloth, or even the plant flats used for carrying pots can be used. They are easy to set up and can be used year after year. Learn more about shading your plants in this link to a previous blog post:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=55005
Be sure to look at our Master Gardener Program website to find a wide variety of useful information. Our previous blogs can also be found here: https://ccmg.ucanr.edu/
Help Desk of the UC Master Gardeners of Contra Costa County (SMH)
- Author: Help Desk Team
It is not unusual to find tomato seedlings for sale in local nurseries and big box stores as early as February or March. Don't make the mistake of rushing to plant them in your garden. In our County it is much too early to put tomato seedlings in the garden, but it is the perfect time to make plans for a bumper summer crop of garden-ripened tomatoes.
When should you plan to plant tomato seedlings in the garden? The easiest way to determine when it is time to plant is to check the soil temperature. The soil should be no less than 60º Fahrenheit when you transplant tomato seedlings. When soils will reach that temperature will depend not only on the climate of the garden location but also on soil type. Sandy soils will warm sooner than clay soils, and soil or potting mixes in containers and raised beds will warm more quickly than soils of in-ground garden beds.
To check, use a thermometer—a soil or kitchen type both work--and measure the temperature at a depth of four inches below the soil surface. Check early morning when the soils are at their lowest temperature. The soil temperature will reach and maintain at least 60º F only after daytime highs are reliably in the 60's and overnight temperatures don't fall below 50º. In Contra Costa County those temperatures generally are achieved late April or early May. If you transplant seedlings by the end of May, the plants still have time to produce well.
So, you still have at least two months to get ready to plant tomato seedlings in your garden. Use that time to decide which tomato varieties you'll grow to get the best results. Two important topics to consider are identifying varieties that will grow well in your local climate and choosing varieties with resistance to diseases that may have been a problem in prior years.
If you live in a cool, foggy or windy climate, choose varieties with shorter “days to maturity”. “Days to maturity” is the estimated time the tomato variety will take to start producing harvestable tomatoes after seedling transplant to the garden. Tomatoes requiring 75 or fewer days are more likely to produce crops in cool climates than those with longer maturity. Most cherry tomato varieties need less than 75 days to start producing, and you can also find some “slicer”,” paste” and “beefsteak” tomato varieties that reach maturity in 75 or fewer days.
If you live in the hot, dry climate found in interior areas of our County, look for varieties with good heat tolerance. They may include both varieties with short days to maturity and those with longer maturities. An internet search for “tomatoes for hot, dry climates” will identify sites with lists of tomatoes well adapted to grow and produce in such conditions.
If you have had disease problems when growing tomatoes in your garden in prior years, try to determine which disease was present. These links provide information that you can use to diagnose and manage common tomato diseases and other problems: https://ipm.ucanr.edu/home-and-landscape/tomato/index.html (Managing Pest in Garden) and https://ucanr.edu/sites/ccmg/files/140320.pdf (Tomato Growing Tips).
Often disease pathogens remain in the soil long after diseased plants are removed. If you've had disease problems, grow your tomatoes in a garden bed where you haven't previously grown tomatoes or other members of the Solanaceae (nightshade) plant family such as peppers, eggplants and potatoes. If your garden area is small and you don't have a disease-free planting area, grow your tomatoes in large containers or plan to plant hybrid varieties instead of heirloom varieties.
Heirloom tomatoes are “open pollinated” varieties that are grown from seeds passed down for more than fifty years. Seeds from open pollinated varieties grow plants that are a genetic match to those of the parent plant. A shortcoming of heirloom tomatoes is that they rarely possess resistance to common tomato diseases.
Hybrid tomatoes are varieties that are created by intentionally cross-pollinating two or more tomato varieties to achieve desired characteristics which may include disease resistance. Seeds from hybrids won't produce matching tomato varieties, so don't bother to save their seeds. If you have identified a disease that has caused problems in your garden, choose tomato varieties with resistance to the disease. Seed packages and descriptions of tomatoes in seed catalogs typically include letter codes to indicate any disease and pest resistance. Common codes include:
- V: Verticillium wilt
- F: Fusarium wilt; a code such as FF or FFF indicates resistance to multiple strains
- T: Tobacco mosaic virus
- A: Alternaria
- EB: Early Blight
- LB: Late Blight
- N: Nematodes (not a disease but microscopic worms that feed on plant roots
If you don't know the disease resistance of a tomato variety you want to grow, you can likely find it on this Cornell University website:
https://www.vegetables.cornell.edu/pest-management/disease-factsheets/disease-resistant-vegetable-varieties/disease-resistant-tomato-varieties/ You may not find tomato varieties with disease resistance to all tomato diseases. For those diseases, be sure to check the UC websites referenced above for tips on managing the disease.
Once you have identified tomato varieties you would like to grow, check with your local nursery to see if it plans to carry them. If you plan to shop the Great Tomato Plant Sale (GTPS) sponsored by UC Master Gardeners of Contra Costa County, you will find a list of tomato varieties that will be available at https://ccmg.ucanr.edu/EdibleGardening/GreatTomatoPlantSale/ If you aren't sure your targeted varieties will be available locally, it's not too late to order seeds and start your own plants. It will only take about six weeks from the time you plant seeds to have seedlings ready to transplant to the garden. Stay tuned for our next blog post to get tips for caring for seedlings and transplanting them to the garden. And mark your calendars for the GTPS which will be held “in person” at the Walnut Creek Our Garden location on April 1, 2, and 3 and at the Richmond Library on April 29.
photo credit: Terry Lippert
Help Desk of the UC Master Gardeners of Contra Costa County (TKL)
- Author: Help Desk Team
A great way to get a head start on your spring and summer vegetable garden!
The seeds of many vegetable plants can be planted indoors several weeks before the usual outdoor planting date. In addition to the bonus of earlier harvest times, your young plants are protected at their most vulnerable stage from inclement weather and the hungry pests that love to feast on small, tender vegetable plants. Planting from seed also gives you access to a much wider variety of vegetables than you would get when purchasing seedlings from local nurseries or big box stores.
Most of us are not lucky enough to have a heated greenhouse or cold fame. Despite that, you can have success starting seeds indoors as long as you provide the conditions they need to germinate and grow. Here are some tips for successful indoor seed starting:
· Purchase your seeds from a trusted source. Fresher, higher quality seeds will have a higher germination rate (meaning more will sprout). Know your local climate zone and last frost dates and choose varieties that are appropriate for your area.
· Some vegetables do best when their seeds are planted directly into the garden. Peas, beans, and most root crops such as carrots, beets, and radishes are some of them. Check the information on the backs of seed packets and consult the CCC Vegetable Planting Guide below to find out which of the plants you wish to grow can be started early, and those that should be directly seeded in the garden.
· Time your seed planting. Not all vegetable plants grow at the same rate. From seeding to planting in the garden, tomato plants can take 5–8 weeks, while cucumbers or melons take 3–4 weeks. Plan your seed planting so that your plants are ready to go outside when the soil and air temperatures are sufficiently warmed up. A good rule of thumb is to wait to transplant outdoors when nighttime temperatures are consistently above 50°F. For more information on the timing of planting, check the backs of seed packets and the CCC vegetable planting guides provided below.
· Use a seed-starting mix. These mixes don't contain any actual soil, but they provide ideal conditions for sprouting seeds. Most importantly, they provide a good balance of drainage and water-holding capacity. Soilless mixes commonly contain some combination of these materials: peat moss, sphagnum moss, perlite, and vermiculite. Don't use garden soil as it doesn't drain well and may harbor plant diseases.
· Container choices. A wide variety of containers can be used- just make sure they are at least 2 inches deep. Recycled containers such as empty plastic yogurt or takeout containers work well. Make sure to poke holes in the bottom that will allow excess water to drain out. Used plastic plant pots, six-packs and flats are good choices and can be reused for many years but should be sanitized before reuse.
· Sanitizing previously planted containers. Remove all soil and debris by scraping, brushing, and rinsing. Use a solution of 9 parts water and 1 part bleach to kill any possible plant pathogens. Soak plastic and other non-porous containers in a bucket of this solution for 10 minutes. Porous containers such as terra cotta should be soaked for 3 hours to overnight. Rinse thoroughly and allow to dry before using.
· Plant seeds at the proper depth. Check the seed packet for planting depth recommendations. You don't need to be too precise, just be sure not to plant any deeper than the directions suggest. The general rule is to plant the seed two to three times as deep as the seed is wide. For example, large seeds like beans should be sown about an inch deep, and very tiny seeds should be barely covered by the soil mix. Tamp down the soil very gently after planting and water right away to thoroughly moisten the soil (until excess water runs out of the drain holes). You will not always get 100% germination, so plant a few extra seeds.
· Don't forget to label all your containers. Do this before or while you are planting your seeds. Use materials that will stand up to wet conditions. Pencil on plastic or wooden stakes will work well.
· After sowing, set the containers in a warm location. Most vegetables germinate best at temperatures between 65° and 75°F. A warm location in your home is one option. Another is to invest in an electric heat mat. They are made specifically for starting seeds and growing indoors, are an excellent way to provide consistent warmth, and will last for many seasons. Find heat mats online or at local garden shops and nurseries.
· Keep the seed-starting mix moist, but not soggy. Plant roots need both air and water. Saturated soil can cause seeds to rot and seedlings to die. Also do not allow soil to dry out. Check daily and water as needed. Clear plastic dome covers or plastic bags (be sure to keep them from touching the soil surface) can be used to help keep the soil evenly moist. Remove the covers after germination to allow for air circulation and to help avoid fungal diseases.
· As soon as seedlings emerge, make sure they get bright light. Placing them next to a sunny window is an option, but containers will need to be turned occasionally to keep the plants growing straight. Better results can be obtained by providing additional light from 40-watt cool white fluorescent tubes. Suspend the lights about 4¬–6 inches over the tops of the plants and keep them on for 14–16 hours each day. Be sure to move the lights higher as the plants grow taller.
· When the seedlings have one or two sets of true leaves, it's time to thin and transplant. If planted in individual pots, you will want to remove all but one seedling per pot. Cut or pinch extra seedlings off at the soil line. If several seeds are planted in flats or small cell packs this is the time to transplant them into larger individual pots. Four inch or quart size containers will give seedlings enough room to grow until it is time to plant in the garden.
· Begin to fertilize weekly. Plants that remain in the seed starting mix will now need added nutrients. When your seedlings have one set of true leaves (see illustration below), use a half-strength fertilizer (liquid fertilizers are easier to use and apply). Organic mixed fertilizers are a good choice. Many of them will provide a range of nutrients that include micronutrients. You may decide to transplant your seedlings into a potting mix that already contains added nutrients, in this case adding fertilizers may not be necessary.
· Be sure to see our upcoming blog posts- on March 6th the blog will provide tips for preparing to grow healthy tomatoes at home, and the March 20th post will be on transplanting your vegetable seedlings into the garden.
Illustration and photos courtesy of S. Hoyer
Seed Sources:
https://sonomamg.ucanr.edu/files/29795.pdf
Vegetable planting guides:
Contra Costa County Vegetable Planting Guide-Interior Regions
Contra Costa County Vegetable Planting Guide-Coastal Regions
Climate zones and last frost dates:
https://cagardenweb.ucanr.edu/Your_Climate_Zone
Local Frost Dates for Garden Planning
More information on vegetable gardening can be found in the links below:
https://cagardenweb.ucanr.edu/Vegetables/
Vegetable Gardening Handbook for Beginners
Help Desk of the UC Master Gardeners of Contra Costa County (SMH)